The present disclosure herein relates to a conditioner of a chemical mechanical polishing apparatus, and more particularly, to a conditioner of a chemical mechanical polishing apparatus, which evenly supplies slurry to a substrate mounted on a carrier head by evenly dispersing slurry over a platen pad of a polishing platen through exact introduction of a predetermined normal force into the platen pad.
Generally, a Chemical Mechanical Polishing (CMP) process is known as a standard process for polishing the surface of a substrate such as a wafer for fabricating a semiconductor including a polishing layer, by counter-rotating the substrate and the polishing platen.
FIG. 1 is a view illustrating a typical chemical mechanical polishing apparatus. As shown in FIG. 1, the chemical mechanical polishing apparatus includes a polishing platen 10 having a platen pad 11 attached thereon, a polishing head 20 mounted with a wafer w to be polished and rotating while contacting the upper surface of the platen pad 11, a conditioner 30 applying a predetermined normal force on the surface of the platen pad 11 to finely cut the surface of the platen pad such that fine pores formed in the surface of the platen pad 11 are exposed.
The polishing platen 10 is attached with the platen pad 11 formed of a polytex material for polishing the wafer w, and rotates due to the rotation of a shaft 12.
The polishing head 20 is disposed over the platen pad 11 of the polishing platen 10, and includes a carrier head 21 gripping the wafer w, and a polishing arm 22 performing a reciprocating motion within a predetermined distance while rotating the carrier head 21.
The conditioner 30 finely cuts the surface of the platen pad 11 such that numerous fine foaming pores serving to contain slurry mixed with abrasives and chemical materials are not blocked, and thus smoothly supplies the slurry filled in the fine foaming pores of the platen pad 11 to the wafer w gripped by the carrier head 21.
For this, the conditioner 30 includes a motor and a gear box therein such that a shaft 33 connected to the holder 32 is rotated, in a state where a holder 32 is gripping a conditioning disk 31 contacting the platen pad 11 during the conditioning process. A cylinder is installed in the housing 34 to apply a downward force 31p to the conditioning disk 31 by pneumatic pressure. An arm 35 extending from the housing 34 performs a sweep motion to finely cut the foaming pores over the wide area of the platen pad 11. For the fine cutting of the platen pad 11, the conditioning disk 31 may include diamond particles attached on the surface thereof contacting the platen pad 11. Also, the shaft 33 may be rotated by a driving motor (not shown) installed outside the housing 34.
Thus, in the typical chemical mechanical polishing apparatus, the wafer w to be polished rotates while being attached to the carrier head 21 by vacuum pressure and pressed on the platen pad 11, and at the same time, the platen pad 11 rotates. In this case, slurry supplied from a slurry supplying unit 40 may be supplied to the wafer w that rotates while being fixed on the polishing head 20, in a state where the slurry is contained in numerous foaming pores that is formed in the platen pad 11. Since pressure is continuously applied to the platen pad 11, openings of the foaming pores are gradually clogged to obstruct the slurry from being smoothly supplied into the wafer w.
In order to overcome such a limitation, the conditioner 30 includes a cylinder applying a pressure toward the platen pad 11, rotating the conditioning disk 31 while applying a pressure to the conditioning disk 31 attached with particles such as diamond particles of high hardness. At the same time, the conditioner 30 performs a sweep motion to continuously perform fine cutting on the openings of the foaming pores that are distributed over the whole area of the platen pad 11. Thus, slurry contained in the foaming pores over the platen pad 11 can be smoothly supplied to the wafer w.
In this case, if the conditioning disk 31 of the conditioner 30 is not pressurized with an adequate force, the openings of the foaming pores of the platen pad 11 may not be opened to obstruct slurry from being smoothly supplied to the wafer w. If the conditioning disk 31 is pressurized with an excessive force, the openings of the platen pad 11 may be opened but the lifespan of the platen pad 11 may be shortened to reduce the economic efficiency.
Although the vertical force of the conditioning disk 31 is controlled by the cylinder such that a predetermined force is applied, the normal force that is substantially applied on the surface of the platen pad 11 may be lost at an intermediate path, for example, a joint of the conditioner 30 that transmits the normal force, or a desired normal force may not be transmitted due to an error of the normal force that may be caused by a cylinder used for a long time. Accordingly, there is a limitation in that slurry contained in numerous foaming pores of the platen pad 11 is not smoothly delivered to the wafer.